The present invention relates to X-ray diagnostic apparatuses.
For diagnosing hip-joint trouble often found in infants or scoliosis in youngsters, the affected parts of a human body are frequently subjected to X-rays for radiographing. These affected parts are relatively near the reproductive gland. The X-ray irradiation on the reproductive glands, therefore, is inevitable during the radiographing operation, to possibly impair its generative function. To lessen the adverse effect on the reproductive glands, it is desirable that the dosage of X-rays be as low as possible. For this reason, the X-ray apparatus has been made to emit the lowest possible dosage of radiation which can be recorded on a sensitized paper or film with a high sensitivity. An example of this type of conventional X-ray diagnostic apparatus is schematically illustrated in FIG. 1.
In the FIG. 1 X-ray diagnostic apparatus, X-rays are radiated from an X-ray tube 1, and are formed, by an X-ray diaphragm (collimator) 2, into an X-ray beam with a diameter sufficient to provide a desired irradiation field. An object 3 under diagnosis is irradiated with the X-ray beam. The X-ray beam transmitted through the object 3 is captured by a radiography device 4 of the low dosage type. The radiography device 4 transforms the X-ray beam into visible light rays containing image information and brings it up to a satisfactory intensity. A grid 5 for removing X-ray scattering is located on the front or X-ray incident side of the radiographic device 4. The X-rays transmitted through the grid 5 hit a fluorescent plate 6 located on the rear side of the grid 5 where the X-rays are transformed into visible light rays containing the image information. The visible rays from the fluorescent plate 6 are passed through a lens 7 and applied to a light image intensifier 8. The intensified visible rays are then projected onto a film in a camera 10, thereby forming an object image thereon. The FIG. 1 apparatus is further provided with a high voltage generator 11 for generating a high voltage for the X-ray tube 1, and an X-ray control unit 12 for controlling the tube voltage of the X-ray tube, a tube current and X-ray irradiation timing. Actually, the film for the camera 10 is a sensitized film of high sensitivity (for example, A.S.A. 3,000) to ensure the formation of an image with a low dosage of X-rays.
As described above, the conventional X-ray diagnostic apparatus is so arranged as to intensify the visible rays and apply them onto the film. Because of this arrangement, the image visualized has a low contrast and is noisy (a low S/N), providing unsatisfactory diagnosis.
The X-ray diagnostic apparatus as shown in FIG. 1 is carried on a mass examination car for diagnosing scoliosis, for example. A layout inside the car is as illustrated in FIG. 2. In the car, the character A designates the radiographic device. For radiographic diagnosis, the patient is laid on a table B having a foot rest in a given posture. The X-ray tube 1 mounted on an X-ray tube rail D is slid along a rail D up to a position C1, and radiates X-rays. The car further carries a mirror camera E for photographing a breast and a film changer F for direct radiographing. The X-ray tube 1 is slid along the rail D and is set at any one of positions C1 to C3 for radiographing. The tube 1 is also swingable in any horizontal direction at each position C1 to C3. In the figure, G designates driver seats, H a doorway and I a changing room for patients. Reference numeral 11 designates a high voltage generator containing a high voltage transformer 11A and a high voltage capacitor 11B, and 12 an X-ray controller. In diagnosing the patient, it is necessary to know the curvature of his vertebra precisely. To this end, in what position to pose the patient is a significant matter. When using the conventional X-ray diagnosis apparatus, before radiographing the affected part, an operator in an X-ray control room goes to a radiographing room where a patient resides and positions him in an optimum posture. Then, he comes back to his room and starts the radiographing operation. The radiographing work is very ineffective since it needs a long time for the preparation of the radiographing operation. During the radiographing operation, the operator is in the control room and cannot check whether or not the patient's posture is maintained as previously set. Therefore, the X-ray image taken in such a way using the conventional X-ray diagnostic apparatus is unreliable for providing an exact diagnosis of the disease.